Method of maintaining a source of light in a desired position in lanterns



' HAGLW? July 10, 1923.

C. O. HARRINGTON METHOD OF MAINTAINING A SOURCE OF LIGHT IN A DESIRED POSITION IN LANTERNS Filed March 22 1921 '7 Sheets-Sheet l July 10, 1923. 1,161,187

, C. O. HARRINGTON I METHOD OF MAINTAINING A SOURCE OF LIGHT IN A DESIRED POSITION IN LANTERNS Filed March 22 1921, 7 Sheets-Sheet 2 45 fl-A 6 57 FA 64 v 101 628 420 V 04. LL 10 66- 42 5 -66 .1 l 33 3 I 7172 I 0 I 52 July 10, 1923. a

' HAELIIS? C. O. HARRINGTON METHOD OF MAINTAINING A SOURCE OF LIGHT IN A DESIRED POSITION IN LANTER s Filed March 22 7 Sheets-Sheet 5 Jufiy m, W23. s. Q. HARRENGTQN METHOD OF MAINTAINING A SOURCE OF LIGHT IN A DESIRED POSITION IN LANTERNS Filed March 22 1921 7 Sheets-Sheet 4L July 10, 1923. RAMA? c. o. HARRINGTON METHOD OF MAINTAINING A SOURCE OF LIGHT IN A DESIRED POSITION IN LANTERNS Filed March 22. 1921 7 Sheets-Sheet 5 w I ll vii/12f" jff WW1 Jufly 1Q, 1923. fiAfiLHW? C. O. HARRINGTON METHOD OF MAINTAINING A SOURCE OF LIGHT IN A DESIRED POSITION IN LANTERNS Filed Marcy; 22

1921 7 Sheets-Sheet 6 nun nmmw 1%] p July 10, 1923.

c. o. HARRINGTON .M'ETHOD OF MAINTAINING A SOURCE OF LIGHT IN A DESIRED POSITION IN LANTERNS Filed March 22. 1921 '7 Sheets-Sheet 7 Lanim ?etenteel duty 1%, 1923 warren stares,

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CLINTON O. HARRINGTON, F CHICAGO, ILLINOIS, ASSIGNOR T0 AIJDOEILT CUKPW,

OI CHICAGO, ILLINOIS. A CORPORATION OI" ILLINOIfi.

METHOD OFMAIN'IAINING A SOURCE OF LIGHT IN A DESIRED FOSI'IIOBI IN Application filed March 22, 1921.

To all whom it may concern:

Be it known that I, CLINTON O. HARRING- TON, a citizen of the United States, and a resident of Chicago, in the county of Cook 5 an'd'State of Illinois, have invented a cer-,

. tain new and useful Method of Maintaining a Source of Light' in a Desired Position in Lanterns, of which the following is a specification.

My present invention relates to methods for maintaining by replacement from time to time, the source of light in lanterns adapted to project rays of light in a given direction, for instance in such lanterns as may be employed for railway signals, locomotive and other headlights, motion picture machines, etc.

Lanterns of the kind to which the present improvements are chiefl applicable include a lens or a reflector for irecting the rays of light. The source of light is frequently an electric bulb in which the incandescible filament is concentrated, that is, confined to comparatively small distances from a'middle point, the ob ect of the concentration of the filament being to produce the desired quantity of light from as small an area or space a'sxis conveniently and practicall possible.

A is well understood, the most e cient. proction of light from the lantern is had when the maxlmum number of rays emanate from a small area or space at the focus of the lens or reflector, and therefore the aim in such cases often is to have the concentrated lamp ,35 filament as close to such focus as conveniently may be. In any event the object is to adjust the filament to that position in which it gives the best results.

' Comparatively few of the concentrated to filament lamps found in service have their respective filaments in such exact relation to the base or plu element of the lamp as to make the lam s interchangeable, wherever they may be deslred to be used, and provide 5 the desired result of a substantially exact focusing of the source of light. It is therefore highly desirable in practice to adjust each lamp individually in the lantern in which it is to be used.

5 The usual practice in railway signal work, when applying a new lamp to a lantern, is

for one man to mount the mast or other the lantern and mastructure supportin ljustably while another nipulate' the lamp a fieljial No. 454,4M1.

man takes a osition say a thousand feet down the tree and observes the results of the various adjustments bein made, this work being done in the night time, the man down the track signaling with a lantern as to the results, and thus in the course of say from one to three hours the lamp is focused sufliciently well for service. Sometimes within a few hours the so-installed lamp burns out, when it becomes necessar to install another in the same tedious an laborious' way. I

The chief object of the present improvements is to rovide a method for focusing the lamp wit greater ease, celerity, and, for the most\,part, with greater accuracy than is possible according to the means and methods heretofore em loyed. In my copending ap-- plication, Serial No. 474,543, filedJune 2, 1921, entitled Focusing finders for lanterns, I have illustrated a finderdevice of the same general character as the one herein shown, which also may be conveniently in the form of an attachment device, for showing to the person making the several adjustments, and during the adjustments, the relative positions of the source of light so that the work of initially adjusting the source may be facilitated, and means, which may be the same attachment device, next hereinabove mentioned, from which a reading and a record may be made of the critical relative position of the source of light in which it is most efiective for that, particular lantern, as determined by the practical test method mentioned or in any other ap roved' way, whereby when a new source 0? light, (ac cording to present practice an electric lamp) is applied the several" adjustments may be made according to the record, in an exceedingly short space of time, and while dispensing entirely with the service of an observer on the track. In the embodiment of the improvements in this respect herewith illustrated, beams from the source of light fall in limited areas or spots upona chart device, and when the source of light is in its desired critical relative position a readin and record of the position of these spots 0 light upon the chart give the desired data from: which other lamps later inserted in that lantern may respectively be adjusted into the desired critical relative position.

The present objects include the obtaining of advanta eous results of the character thus indicate Other objects and advantages will appear hereinafter.

In the accompanying drawings, which form a part of this specification, Figure 1 "shows a well-known form of railwa signal Fig. 4 is atop plan of the same; Fig. 5 is a side elevation of the same similar to that shown in Fig. 1; Fig. 6 is a sectional elevation on the line 6-6 of Fig. 5; Fig. 7 is a fragmentary horizontal section showing parts of Fig. 6; Fig. 8 is a perspective of the main support; Fig. 9 is atop view of the optical device attachment or finder; Fig. 10 is a side view thereof; Fig. 11 is a section on the line 11--11 of Fig. 10, this figure also showing different relative positions of the source of light and the direction of.,indicating-light-beams through the finder there from ;-Fig. 12 is a horizontal section on the line 1212 of Fig. 9; Fig. 13 is an end view of the finder showing the chart'device; Fig. 14 is a view of the finder device from the other end; F ig. 15 is a sectional 'view on the line 15-45 of Fig. 10,; and Fig. 16 is a face view of a card or sheet showing a record. All sectional views are in the directions of the arrows respectively.

The lantern 20, Fig. 1, of well-known construction. It has a lens ,21 in front and a vertically slidin'g'door 22 permitting entrance from the rear. It is to be understood that the lantern is secured to a signal mast or other structure, and at a considerable elevation above the railroad track. Ordinarily there is a spectacle having several differently colored glass screens or froundels operatively positioned in front of the lens whereby different signals may be given through the movement of the spectacle device, 'all as is well understood in the art. The mounting of the lamp above the ground and the use 1f desired of such a 10 are not illustrated but are mentioned to show the a plication of these improvements a rai way signal lantern of that type. The desideratum is that the lamp within the "lantern shall be kept burning with as little less of time at replacement periods as possible, and with the lamp so positioned as to project light most efiiciently. v

Lamp adjusting d'evice.-The lamp 23 is adjustably mounted on several-flames which are carried by a unitary su .port L-shaped in side view and which is we shown in pervspective in Fig. 8. This support comprises a base 24, 25 which is T-shaped, the leg 24 extending forward. Screws 26, Fig. 1, hold this base member rigidly upon the bottom wall of the lantern. From the end portions of the base head 25 the side members 27 rise vertically, the structure turning inward at 28, and then rising vertically'again in the side members 29, these side members being joined by the top member 30. Apair of inetegral lugs 31, 32 extend laterally from the side members 27, and these lugs are bored vertically in alignment at each side to receive the rods 33 respectively which rods are held rigidly in the lugs, as by means of pins. A normally vertical rod 34 is secured midwag between the side members 27, Fig. 3, an

The frame which provides for vertical ad-' justments carries the other two frames and will next be described. It comprises first an open rectangular frame having two side members 40, an inner end or cross member 41, and at its other end a cross member'42 which extends upward and lies largely just back of the support members 27, 28 and 29. It has two lateral, rearward extensions 43,

that is they extend toward the door of the lantern as viewed in Fig. 1, and these are nicely bored so as to fit s'lidingly upon the upright rods 33. Thecross member 42 has two middle rearward' extensions, one 44 above and one below, which are bored nicely to fit for sliding movement upon the fixed rod 34. It is clear that the vertically adjustable frame, whichI will denominate as a whole as V will be bound to move in lines, as to all ofTts parts, which. are strict] parallel to each other and normall in vertical direction when the frame V s ides upon the rod supports 33 and 34.

Means for moving the frame V in vertical directions include the screw threads 46 on the supportingl rod 34 and a finger wheel 47 up'onthe t reads 46. The finger wheel. 47 has oppositely disposed integral collar parts 48 and these are en aged by a pair of upper oppositely-disposed forward pro'ections' 49 and a pair of lower opposite] isposed projections 50 which are tegn? with extends from the base head 25 to the the upright parts 42 of the frame V, the weight of the frame V bein therefore carried upon the fin er wheel 4 and'the screw 46. It is clear t at by rotating the finger wheel 47 the frame V will be moved either up or down.

' It will be noted that the finger wheel 47 has recesses 52 in its periphery and that these recesses are engaged y a lug 53 on a leaf spring 54, Figs. 5 and 6, the leaf spring being held on the stud 55 and the pressure upon the leaf spring being controlled b a thumb nut 56 threaded upon the stud. The leaf spring 54 lies in a recess 57, Fig. 6, and is therefore held in its normally substantially vertical direction and it thus holds the finger wheel 47 against movement except through a manual operation.

I have thus shown how the frame Vfis caused to move up and down at the oper ators will. It is next in order to show how the second frame, being the one to provide fore-,and-aft adjustments, is operatively carried by the frame V. I a

This frame for fore-and-aft adjustments will be indicated bodily as frame F-A. It comprises a rear cross member 60, a forward cross member 61 and a lateral or fore-andaft cross member 62. The frame V is pro-' hexagonal collar 69 rigid upon it and in engagement with the wall 42, Fig. 6, of the frame V.- The member 42 has an enlargment or hearing 70 (Fig. 2) and the shaft 68 extends loowly therethrough for rotative movement. An enlarged collar or head 71 is secured rigidly, as by a cross pin, upon the outer end of the shaft 68, and this collar 71 bears J inst the enlargement 70 of the wall 42. circular recess 72 is formed in the outer end of the collar or head 71, and a transverse slot-.73, to accommodate a screw driver, is formed in the head 71 within the recess 72. The screw driver slot 73 is thus surrounded by a flan and the adjuster, often making the adjustment at night, is thus enabled to position the screw driver first in the recess 72 and then easily in the slot 78.

According to the construction thus far latterly described it is clear that by turning the head 71 the screw shaft 68 will be turned, but without any longitudinal movement, and that the frame F-A will bemoved in fore-and-aft directions through the engagement of the screw shaft 68 with the threaded lug 63 on the frame F-A.

The screw shaft 68 is prevented from turning except when manually operated by means of aspring having an extension 75 which is coiled around a barrel 76 on the thumb nut 56 and presses upon the hexagonal collar 69 on the shaft 68.

The next feature for description is the third adjusting frame, or-the one providing for movement of the lam or source of light in lateral directions. is frame will be indicated as a whole by the letter L. The bottom view, Fi 2, shows that this frame L comprises two ateral parts 80 and 81, a rear transverse part 82 and a forward transverse part 83, this frame being also of hollow rectangular form. By referring to the to view of Fig. 4 it will be noted that the si e member 82 of the frame L has a pair of extensions or cars 84, and that the side member 83 has a similar pair of ears or extensions 85. It is here pointed out that the frame F-A is provided with four upwardly extending ears 86 on one side and 87 on the other side (Fig-.4), and extending through and secured in holes in these ears are the parallel rods 88 and 89. The cars '84 and of the frame L are nicely bored for sliding movement 11 on these rods 88 and 89 and the table or ame L is thereby mounted for movement in lateral directions.

Byrreference to Fig. 2 it will be noted that the ame F-A has a fore-and-aft normally downwardly extending rib 90 connecting the rearwardl extending front frame members 61 with't e rear transverse frame member 60. A transverse screw shaft 92 is mounted for rotative movement in the web 90 and held against longitudinal movement by the collars 93 and 94, the latter one being a part of the bevel gear 95. The part 81 of the frame L is provided with a normally downwardly extending car 96 which is bored and tapped to receive the screw-shaft 92. It will thus be clear that when the gear is rotated the frame L will be moved in one lateral direction or the other b the screw shaft 92 in the nut part 96. aans for rotating the gear 95 comprise the gear 97 mounted on the shaft 98 which has a bearing in a downwardly projecting bearing member or extension 99 which is integral with the frame parts 61 of the frame F-A.. The gear 97 is held against longitudinal movement by the collar 160 on one side of the bearing member 99 and by the collar 101 on the other side thereof. The'collar 101 has its end portion recessed at 102 and provided with a screwdriver slot 108. The collar 101 has a substantially long hexagonal part, as well illustrated in Fig. 2, against which presses the spring extq sion 104, this spring maintaining the shaft 98 against accidental rotatiremovement. By reference to Fig. 6 it will be noted that the frame V is cut away at 105 whereby the frame F-A may move in its fore-and-aft directions relative to the frame V without interference by this forwardly projecting part 101, As the foreand-aft adjustments are made the spring 1021 applies itself to a new portion of the hexagonal collar 101 in the longitudinal directions.

The lamp 23 has a concentrated filament 109; The leads forthe electricity to the lamp are not shown, but in ractice they are connected to the termina s 110, Figs. 3 and 4. The lamp socket or base 111 is secured by screws 112 upon the frame L.

Briefly stated, the lamp adjustment device includes a base which has at one end a middle vertical rod and two lateral vertical rods rigid with the base. A vertical adjustment frame or table is carried on these three rods slidingly, the lateral vertical rods 33 maintaining the frame Vv against lateral swinging movements and the upper and lower sliding connections 44 and 45 in engagement with the middle rod'34 maintaining the table V against swinging up-and-down movements, the construction providing that.

the table V must always move in directions at right angles to the base, or, stated otherwise, in lines parallel with the two side rods 33 and the middle rod 34. On the table V is mounted a second table F'-A having movements in fore-and-aft directions relative to the table V. on the table FA is mounted the table L having movements in lateral directions with res ect to the table FA; and on the table is mounted the source of light.

It will be noted also that each of the three adjustments can be made by the operator from what I have described as the rear end of the device, namely that end adjacent to the doorway of the lantern when the device is in position for use. This feature is quite important and enables the person makin the adjustments to do so easily and quickly and without chan 'ng his somewhat precarious position on t e mast or other structure, and while remaining in full view of the indicating chart presently to be specifically described. It will also be observed that any one adjustment of the source of light can be made entirely independently of any other adjustment made or desired to be made, be it vertical, fore-and-aft, or lat era], and this is highly important in obtaining the desired results with accuracy and expedition.

Optical chart device or finder.-I have provided for use in association with lampadjusting means, for instance such as those herein above described, an optical device which shows in a pictorial way the relative position of the source of light, and shows the lamp movements while the adjustments are being made.

The finder F is preferably in the form of an attachment, and is shown in its oper-v ative position in Fig. 1. Ithas a body portion, in my practice an aluminum casting, to which is secured a bracket 115 as by screws 116, this bracket having in its base a hole 117, Fig. 12, adapted to receive with a nice fit the vertically projecting stud '35 of the adjusting device. The bracket 115 has also a pair of depending legs 118 spaced apart and at theirlower extremities turned laterally at 119, their free ends respectively being provided with a recessed lip or bearing member 120 adapted to press against the front surface of the upwardly projecting studs 36 of the adjusting device. It will thus be seen that the finder F may readily be positioned upon a relatively fixed part, in this instance upon the support of the adjusting device, the finder being held b the fixed vertical rods which carry direct y or indirectly the several adjustment frames, and the finder may be lifted off of these projecting studs after the adjusting operation. One finder will be suflicient for adjusting all of the lanterns along the line which are adapted to receive it, and, in practice, eac'h finder is calibrated on a standard lam and lamp adjustment device wherepy any fi nder may be used for adjusting any amp The body of the finder F comprises walls forming two separate compartments. Compartment A, Fig, 12, has an upper wall 125, a lower wall 126, one side wall 127 and another side wall 128. These walls converge toward the source of light and terminate in an end wall 129 which for purposes of calibration will ordinarily be a separate substantially square plate and be held adjustablv in position by the screws 130. After calibration, however, the plate 129 will ordinarily be sealed in a fixed position, as by a soldering operation. This end plate 129 has a light-aperture, shown as a circular hole 131, the hole being in actual practice about one sixteenth of an inch. The size of the hole may vary somewhat but since its function is to limit the rays of light from the source to such as to provide a relatively small shaft and throw substantially a spot of light of limited area upon the chart it should be, of course, relatively small.

The chamber B of the finder F is defined by an upper wall 132 and a lower wall which is in part the wall 125 and in part a somewhat lateral and rearwardly proceeding extension of the wall 125, indicated in Fig. 11 as 125. It is defined laterally by side walls 133 and 134. From Fig. 11 it is well to be seen that the chamber B is directed forwardly and laterally of the neral direction of the chamber A, the object thereof lid reenter being to form a channel through which may be directed light beams from the source which are projected therefrom substantially at right angles with respect to those passing through the chamber A (the angle being greater or less than a right angle according to the relative position of the source of light-,) a reflector being used to change the direction of the beams desired to be projected through the chamber B. The walls of the chamber B terminate in a throat portion at 136 across which is inserted a plate 137 having a substantially narrow slot 138 which.- is normally vertically disposed. This plate 137 (Fig. and the slot 138 are exposed through a window or opening 139 in the end wall 140 integral with the rest of the casting. From Fig. 10 it is clearly shown that the plate 137 is inserted in a saw-cut in this end wall 140. It may be held there by soldering or in any other approved way. lhe walls of the chamber B extend farther to the right, as viewed in Figs. 9 to 12, and terminate in a head 1 14 which. is bored to provide an annular shoulder at against which rests the glasscr other reflector 146, there being some soft packin 147 back of the reflector, and a plate 148 old by screws 1419 maintains the reflector in its operative position. A pair of strengthening ribs 150 are added for giving suitable strength to the head-extension 1 M.

lit will be noted from. Fig. 1 that the re- -dector 1% is above the concentrated source of light, namely the filament 109. llt is clear that this reflector might have its centell on a horizontal line with the filament 109 and the chamber B might be at one side, rather than above, the chamber A.

That arrangement, however, would make for unnecessary width of the finder device. ln order to economize space and make the finder F a small and compact device I have arranged the chamber B above the chamher A, the reflector M6 naturally thereby finding its position above the source or" light. lln order therefore to compensate for this elevation of the reflector the'refiector is tilted with its top part moved toward the source of light, as is well to be seen from Figs. 9 and 11, the lane of the reflector surface being substantially parallel with the plane of the holding plate 148. Light beams from the source are accordingly reliected through the vertical slot 138, which, in my practice is also about one-sixteenth of an inch in width, and travel forward in the form of a relatively thin vertical sheet.

Turning to Fig. 13 the chart device which covers the entire front end of both chamber hand chamber B is shown. This chart device in my practice is a iece oi ground glass marked in lines by etc "ng, ink or in any other approved way, and is arranged to altord a separate reading for the beams oi? light assing directly from the source throug chamber A and for those passing by reflection through chamber B. For the chamber A there is shown a plurality of equidistant vertical lines and a plurality of equidistant horizontal lines 156. The vertical lines are indicated by the letters A, B, C, etc., while the horizontal lines are indicated by Figures 1, 2, 3, etc. This kind of chart device is not new in itself and this method of indicating locations has been used extensively for instance on maps. The upper part of the diagram or chart, or that which is at the end of chamber B, is divided into vertical lines which are lettered with other letters of the alphabet than those used for the lower chart. It will be observed that the lines M to Y inclusive on the upper chart are not equidistant from. each other but gradually decrease in width from left to right according to a natural progression, the reason for which will be understood from Fig. 11 which shows that light beams from the source S make varying angles of incidence to, and consequently of reflection from, the reflector 1 16 as the source S is moved back and forth. The instrument as illustrated has been calibrated and the relative locations of the vertical lines 157 show substantially equal distances of movement of the source of light.

If the source of light were at oint 158, Fig. 11, which is intended to in icate the approximate focus of the lens, and amuming that the adjustment device has been positioned accurately in the lantern, the vertical shaft of light from the chamber B would correspond with the heavier line 160 of the upper chart, and the spot of light on the lower chart device would be at the middle point 161. In actual practice, however, owing to slight difi'erences in the positioning of the lamp-adjusting device in the lantern, to the fact that the lenses are not uniform, and to the fact also that these incandescent lamps do not have their respective filaments in a precise location with respect to their bases, the position of the light spots upon the chart at 160or point 161 would not ordinarily indicate even an up,

proximate adjustment. lit is enough that when the lamp be posi/ tioned so as to give the most efiicient light for its particular location, whether at the focal point or not, a record may be made of this position as shown by the chart device, for future use.

With this understanding of the construction and application of the finder device to the adjusting device the two principal uses of the finder may be described. The first use occurs when the initial or first lamp is adjusted. Ordinarily to get this first adjustment the adjuster will mount the sigmol meat or other structure on which the This is immaterial;

lid

till

Elli) is carried while a man with a lantern will take a position at the desired distance down the track. If now the adjuster will move the lamp laterally until the man down the track has si aled that it has faded out at one side, an then move the lamp in the opposite direction until the signal is received that the light has faded out in the opposite direction, the operator can, by bisecting the distance indicated on the chart device, ascertain the desired position for the lam in the lateral directions. Similarly the fa ing out points are noted for the vertical adjustments and by simply bisecting these distances the proper point on the chart is arrived at for the vertical adjustment. The fore-and-aft adjustments are continued unil the Signalman indicates that the pro er spread and intensity of light is obtaine We will assume for purposes of illustration that the place in which. the lamp is found to be most effective is indicated by the dotted oblong spot of light 165, and that the shaft of light indicatin the pro r foreand-aft ad ustment is ound to ave the position indicated by the dotted lines at 166, Fig. 13. The adjuster will then proceed to make a record, either in a book, or oina card which he may leave in the lantern, for instance the record card of Fig 16, which indicates that the spot of light 165 showing lateral and vertical adjustments is at the intersection of lines E and 7, while the shaft of light showing the fore-and-aft ad'ust ment is between the lines P and Q o the chart device.

It is now clear that at any future time when it is desired to replace the electric lamp the services of the observer down the track ma be dispensed with, and the ad juster, tahin with him the finder device, may go to t e lantern, substitute the new lamp for, the burned-out one, ap ly the finder as before, consult the record or that lantern and thereby observe where the spot and shaft of light respectively must be, and then adjust the lamp until spot 165 and beam 166 fall at the indicated places on the chart. Insome instances this critical relative position is not at the focal point, as the presence of a curve in the road may call for some other relative position, as well understood in the art, but whatever the relative position is for that particular lantern the record previously made shows it, and new lampscan always be so positioned according to the record made through the use-of the chart device. The drawings herein are substantially true to scale.

Reference should be had to thg appended claims to determine what I consider to be included in the scope of the present advance in the art.

I claim:

. 1. The method of maintaining, by replacement of the light-giving member, a source of light provided by such light-giving member and a light-projecting member substantially in a desired critical relative position with respect to each other and in which replacement the second light-giving member would not provide the source of ii ht substantially in its desired critical relative position with respect to the light-projectin member without adjustment of one of said members relative to the other, which comprises, first, placing, in any approved way, the source of light provided by such lightgiving member and the light-projecting member substantially in their desired critical relative position with respect to each other; second, recording this critical relative position according to the readings of an optical instrument seated on a part of the lantern in a definite relative position and adapted to indicate various relative positions of the source of light from such lightgiving member with respect to the lightprojecting member; third, replacing the first light-giving member by a second lightg'iving member; and, fourth, adjusting one of said members relative to the other while the person making the adjustments observes from such optical instrument, while the adjustments are being made, the effect of such adjustments and until the instrument readings of such optical instrument therefrom su stantially coincide with the record made according to the second step hereof.

2. The method of maintaining, by replacement of the light-giving element, a source of light substantially at its desired critical relative position in a lantern having a relatively small area in which the source of light is most effective and in which replacement the second light-giving element would not provide the source of light substantiall in its desired critical relative position without relative adjustment in a plurality of directions after the replacement operation, which comprises, first, locating, in any approved way, the light-giving element so as to provide the source of li ht substantially at its desired critical relative position; second, recording the critical relativegiosition of the source of light when locate according to the first-mentioned stop, such recording being done according to the readings of an optical instrument attached to part of the lantern and capable of indicating various relative positions of the source of light and the light-projecting member; third, replacing the so-located lightgiving element by a second light-giving element; and, fourth, adjusting the second light-giving element in a plurality of directions w ile the person making the adjustments observes from such optical instrument, while the adjustments are being made, the effect of such adjustments and until the relative position of the second lightgiving element substantially agrees with the record made according to the second step hereof.

3. The method of maintaining a source of light substantially at its desired critical relative position with respect to a light-projecting member through the replacement of the light-giving element by another light-giving element which, withoutrelative adjustment after being placed, would not provide a source of light substantially at the critical relative Position desired, which consists first, in locatingthe source of light from such light-giving element in any approved way substantially 'in its desired critical relative position; second, by means of an optical device attached to a part of the lantern in a definite relative position taking a reading of the relative position of the source of light when substantially in its desired critical relative position; third, recording. such reading; fourth, replacing the light-giving element providing the source of light by an other such element; and, fifth, relativel adjusting the second light-giving elemen substantially in accordance with the record made according to the third step hereof while the person making the adjustments observes, as the adjustments are being made, the results of such adjustment by means of the optical device.

4. The method of maintaining a lightgiving member, having a relatively small source of light, in a lantern having such light-giving member and a light-projectin member, one of which members is mounte for adjustment with respect to the other, which consists, first, in adjusting the adjustable one of said members until light from said source is projected by the light-projecting member substantially as desired; sec-' ond, applying to the lantern an optical instrument having means for indicating vaious relative positions of the source of light with respect to the light-projecting memher; third, recording the readings of the optical instrument when indicating the relative position obtained according to the first step hereof; fourth, substituting another light-giving member; and, fifth, adjusting the adjustable member while the person makingthe adjustments makes observations with the optical instrument until the readings of the optical instrument substantially coincide with the record previously made according to the third step hereof.

5. The method of maintaining, without removing from service or disturbing the adjustment of the lantern body, a light-givin member having a relatively small source of i r; in a lantern sitioned and adjusted 1% for use me W 'ch lantern has a hghtt one of said members until light from said light-giving member is projected by the light-projecting member substantially as desired; second, applying to a part of the lantern an optical instrument having means for indicating various relative positions of the source of light of such light-giving member with respect to the light-projecting member; third, recording the readings of the optical instrument when indicating the relative position obtained according to the first step hereof; fourth, substituting another light-giving member fifth, adjusting the adjustable member while the person makingthe adjustment makes observations with 'the optical instrument until the readings of the optical instrument substantially coincide with the record previously made according to the third step hereof; and, sixth, removing the optical instrument.

o 6. The method of maintaining a lightgiving member, having a relatively small source of light, in a lantern having such light-giving member and a light-projecting member, one of which members is mounted for adjustment with respect to the for it a record showing, in terms of the readings of an optical instrument capable of being associated with the lantern and indicating various relative positions of the. source of light of such light-giving member with respect to the light-projecting member, an established relative position of adjustments by means of the optical in-' strument and until the relative position of the source of light of such light-giving member and the light-projecting member substantially coincides with the said established record; and, fourth, removing the optical instrument from the device.

7. The method'of focusing a source of light in a lantern having such source 0t" light and a light-projectingmember and in which one of said members is mounted for adjustment with respect to the other in a plurality of directions, which consists, first, in applying to the lantern an optical inw, capable ct the various tltd other, and which lantern has had prepared Illtl lltti relative positions of the source of light and the light-projecting member in a plurality of directions; second, adjusting the adjustable member in a given direction until the light from the lantern substantially fades out of the view of an observer located at a point in the desired normal path of light from the lantern; third, observing from the optical instrument the relative position of said members when the light substantially fades out; fourth. adjusting the adjustable member in the reverse direction until the light from the lantern substantially fades out, in the reverse movement, as viewed by the observer at his same position as before; fifth, observing from the optical instrument the relative position of said members when the light so again fades out; sixth, adjusting the adjustable member until the optical instrument indicates the relative position of said members to be substantially at point midway between the extreme opposite positions in which the light faded out to the observer, as stated in steps two and four hereof.

CLINTON O. HARRINGTON.

lib 

